WO2021070561A1

WO2021070561A1 - Multilayer body and method for producing same

Info

Publication number: WO2021070561A1
Application number: PCT/JP2020/034516
Authority: WO
Inventors: 章古谷; 忠昭小島; 鈴木　広志
Original assignee: 昭和電工株式会社
Priority date: 2019-10-10
Filing date: 2020-09-11
Publication date: 2021-04-15
Also published as: KR20220004689A; SG11202113223VA; TWI753581B; JPWO2021070561A1; EP4043611A1; TW202125594A; CN113874549A; US20220228266A1; EP4043611A4

Abstract

The present invention addresses the problem of providing a metal material which is applicable to a constituent member of an apparatus for producing a semiconductor, while having excellent corrosion resistance. A multilayer body according to the present invention comprises a metal base material, a nickel-containing plating film layer that is formed on the metal base material, and a gold plating film layer that is formed on the nickel-containing plating film layer; and pinholes in the gold plating film layer are sealed with a fluoride passivation film that has a thickness of 8 nm or more.

Description

Laminated body and its manufacturing method

The present invention relates to a laminate and a method for producing the same. More specifically, the present invention relates to a laminate suitable as a constituent member of a semiconductor manufacturing apparatus or the like, and a method for manufacturing the laminate.

Conventionally, in the semiconductor manufacturing process, halogen-based reactivity and corrosiveness such as fluorine, hydrogen chloride, boron trichloride, nitrogen trifluoride, chlorine trifluoride, and hydrogen bromide in the dry etching process and cleaning of the manufacturing equipment. A strong special gas (hereinafter also referred to as "corrosive gas") is used.

However, when the corrosive gas reacts with moisture in the atmosphere and hydrolyzes, products such as hydrogen fluoride, oxalic acid, and hydrogen chloride are generated. The product is problematic because it easily corrodes the metal surfaces of components such as valves, joints, pipes and reaction chambers when using the corrosive gas.

On the other hand, pinholes on the plated surface can also cause corrosion to progress. The cause of pinholes is, for example, that hydrogen gas generated by the plating reaction becomes bubbles during the formation of the plating film and inhibits the film formation, or impurities (oxide film, dirt, oil, etc.) left on the base material are present. There are multiple possible causes, such as not being removed in the pretreatment step and hindering film formation.

So far, in order to improve corrosion resistance, a method of plating a metal base material with a nickel-phosphorus alloy to form a fluorinated passivation film of nickel has been performed (see, for example, Patent Documents 1 to 3). However, these methods were not always sufficient.

There is also a method of forming a low-temperature and thick nickel fluorinated passivation film by plating a metal base material with a nickel-tungsten alloy _{and using the standard enthalpy of formation of WF 6 generated by a fluorination reaction.} There is a restriction that the applicable members are limited in that it is an electrolytic plating method (see Patent Document 4).

Japanese Patent No. 29541716 Japanese Patent No. 3094000 Japanese Unexamined Patent Publication No. 2004-3600066 Japanese Unexamined Patent Publication No. 2008-056978

The present invention is intended to solve the above-mentioned problems associated with the prior art, and to provide a metal material which is applicable to a constituent member of a semiconductor manufacturing apparatus and has excellent corrosion resistance, and the metal. The purpose is to provide a method for producing a material.

The present invention relates to, for example, the following [1] to [12].
[1] It has a metal base material, a nickel-containing plating film layer formed on the metal base material, and a gold plating film layer formed on the nickel-containing plating film layer, and has the gold plating film. A laminate in which the pinholes of the layer are sealed by a fluorinated passivation film having a thickness of 8 nm or more.

[2] The laminate according to the above [1], wherein the metal base material contains at least one metal selected from the group consisting of stainless steel, iron, aluminum, aluminum alloys, copper and copper alloys.

[3] The laminate according to the above [1] or [2], which has a nickel strike layer between the metal base material and the nickel-containing plating film layer.
[4] The nickel-containing plating film layer is a nickel-phosphorus alloy plating layer (1) having a phosphorus concentration of 8% by mass or more and less than 10% by mass, and a nickel-phosphorus alloy having a phosphorus concentration of 10% by mass or more and 12% by mass or less. The laminate according to any one of [1] to [3], wherein the plating layer (2) is included in this order from the metal substrate side.

[5] The gold plating film layer comprises the replacement type gold plating film layer and the reduction type gold plating film layer in this order from the nickel-containing plating film layer side, according to any one of the above [1] to [4]. The laminate described.

[6] A component of a semiconductor manufacturing apparatus, which comprises the laminate according to any one of the above [1] to [5].
[7] A step of forming a nickel-containing plating film layer on a metal substrate (A), a step of forming a gold plating film layer on the nickel-containing plating film layer (B), and a pinhole of the gold plating film layer. A method for producing a laminate, which comprises a sealing treatment step (C) for forming a fluorinated passivation film having a thickness of 8 nm or more.

[8] The method for producing a laminate according to the above [7], wherein the sealing treatment step (C) is performed in an atmosphere having a fluoride gas concentration of 8% by volume or more and a temperature of 100 to 150 ° C.
[9] The laminate according to the above [7] or [8], wherein the metal base material contains at least one metal selected from the group consisting of stainless steel, iron, aluminum, aluminum alloys, copper and copper alloys. Production method.

[10] The method according to any one of [7] to [9] above, which comprises a step of subjecting the metal substrate to a nickel strike treatment under the condition of a current density of 5 to 20 A / dm ^{2 before the step (A).} Method of manufacturing a laminate of.

[11] The step (A) is a step (a1) of forming a nickel-phosphorus alloy plating layer (1) having a phosphorus concentration of 8% by mass or more and less than 10% by mass, and a phosphorus concentration after the step (a1). The method for producing a laminate according to any one of [7] to [10] above, which comprises a step (a2) of forming a nickel-phosphorus alloy plating layer (2) in which is 10% by mass or more and 12% by mass or less.

[12] The step (B) includes a step (b1) of forming a replacement type gold plating film layer and a step (b2) of forming a reduction type gold plating film layer after the step (b1). The method for producing a laminate according to any one of [7] to [11].

According to the present invention, it is possible to provide a laminate having excellent corrosion resistance, particularly corrosion resistance to acid.

It is the schematic which shows the laminated body before and after the sealing process ((a): before the sealing process, (b): after the sealing process).

Hereinafter, one embodiment of the present invention will be specifically described.
The laminate of one embodiment of the present invention includes a metal base material, a nickel-containing plating film layer formed on the metal base material, and a gold plating film layer formed on the nickel-containing plating film layer. Moreover, the pinholes of the gold-plated coating layer are sealed with a fluorinated passive coating having a thickness of 8 nm or more.

The method for producing a laminate according to an embodiment of the present invention includes a step (A) of forming a nickel-containing plating film layer on a metal substrate and a step (B) of forming a gold plating film layer on the nickel-containing plating film layer. ), And a hole-sealing treatment step (C) for forming a fluorinated passivation film having a thickness of 8 nm or more in the pinholes of the gold-plated film layer.

[Metal base material]
The metal base material used in one embodiment of the present invention is a base material whose surface is at least made of metal. The metal base material is not particularly limited, and examples thereof include metals generally used for constituent members of semiconductor manufacturing equipment, preferably stainless steel, iron, aluminum, aluminum alloys, copper and copper alloys.

In order to strengthen the adhesion to the nickel-containing plating film layer, the metal base material is subjected to a treatment according to the base material such as degreasing, acid cleaning or nickel strike treatment as a pretreatment in the step (A). May be good. The nickel strike treatment is a preliminary plating treatment using a nickel-containing plating bath, and the current density in the nickel strike treatment is preferably 5 to 20 A / dm ² , more preferably 5 to 10 A / dm ² . The nickel strike treatment time is preferably 5 seconds or more and 5 minutes or less.

[Nickel-containing plating film layer]
The nickel-containing plating film layer is formed on the metal substrate by the step (A). When the metal base material is subjected to a nickel strike treatment, a nickel strike layer is provided between the metal base material and the nickel plating film layer.

The nickel-containing plating film layer preferably contains phosphorus from the viewpoint of improving corrosion resistance, and has a nickel-phosphorus alloy plating layer (1) having a phosphorus concentration of 8% by mass or more and less than 10% by mass and a phosphorus concentration of 10% by mass. It is preferable that the nickel-phosphorus alloy plating layer (2) of 12% by mass or more is contained in this order from the metal base material side.

The nickel content in the nickel-containing plating film layer is preferably 80% by mass or more, more preferably 85 to 95% by mass, and particularly preferably 88 to 92% by mass, when the entire nickel-containing plating film layer is 100% by mass. Is. When the nickel content is in the above range, the ratio of phosphorus in the coating layer is increased, and excellent corrosion resistance can be exhibited. In addition, when electroless nickel-phosphorus alloy plating films with different phosphorus concentrations are laminated, pinhole defects are formed at different positions while forming a film, which makes it difficult for disturbances to reach the substrate directly and has corrosion resistance. Improvement can be expected.

<Process (A)>
The nickel-containing plating film layer can be formed on a metal substrate by using an electroless plating bath containing a nickel salt and a phosphorus compound as a reducing agent. Examples of the nickel salt include nickel sulfate, nickel chloride, nickel acetate, nickel carbonate and the like. Examples of the phosphorus compound include sodium hypophosphite, potassium hypophosphite and the like.

The step (A) includes a step (a1) of forming a nickel-phosphorus alloy plating layer (1) and a step (a2) of forming a nickel-phosphorus alloy plating layer (2) after the step (a1). , Is preferably included.

The film forming rate of the nickel-phosphorus alloy plating layer (1) is preferably 20 to 30 μm / h (hours), more preferably 22 to 25 μm / h (hours), and the nickel-phosphorus alloy plating layer (2). ) Is preferably 10 to 15 μm / h (hours), more preferably 11 to 13 μm / h (hours). By forming the nickel-phosphorus alloy plating layers (1) and (2) in this way, the corrosion resistance can be improved. The film thickness of the nickel-phosphorus alloy plating film layers (1) and (2) is preferably 5 μm or more, more preferably 7 to 25 μm, and further 10 to 20 μm from the viewpoint of film performance and cost in which pinholes are less likely to occur. preferable.

[Gold plating film layer]
The gold plating film layer is formed on the nickel-containing plating film layer by the step (B).

The gold content in the gold plating film is preferably 90% by mass or more, more preferably 99% by mass or more, and particularly preferably 99.9% by mass or more, when the entire gold plating film is 100% by mass. .. When the gold content is in the above range, the corrosion resistance of the laminate according to the embodiment of the present invention is stable. The gold content is determined by the impurity quantification method, that is, the gold plating is dissolved in aqua regia and measured by atomic absorption spectrometry and high frequency inductively coupled plasma (ICP) emission spectroscopy.

The thickness of the gold-plated coating is preferably 0.1 μm to 1 μm, more preferably 0.2 to 0.9 μm, and particularly preferably 0.3, from the viewpoint of coating performance and cost in which pinholes are less likely to occur. It is ~ 0.8 μm. It is known from the prior art that the number of pinholes decreases when the noble metal plating film is thickened, and high corrosion resistance is expected, but it is preferable to make the thickness appropriate because the price is high.

<Process (B)>
The method for forming the gold plating film layer is not particularly limited, but an electroless gold plating method is preferable. In the electroless gold plating method, it is preferable to perform reduction type gold plating after performing replacement type gold plating. That is, the step (B) may include a step (b1) of forming a replacement type gold plating film layer and a step (b2) of forming a reduction type gold plating film layer after the step (b1). preferable.

In the replacement type gold plating, nickel is dissolved from the nickel film, and the gold ions in the solution are reduced by the electrons emitted at that time and precipitated as a gold plating film. In reduction gold plating, gold ions in the solution are reduced by electrons released by the oxidation reaction of the reducing agent, and a gold plating film is precipitated.

Examples of the electroless gold plating solution include a plating bath containing potassium gold cyanide, gold chloride, gold sulfite, gold thiosulfate and the like, and examples of the reducing agent include sodium hydroxide, dimethylamine borane and hexa. Examples thereof include methylenetetramine, a chain polyamine having an alkyl group having 3 or more carbon atoms and a plurality of amino groups.

Substitution gold plating, preferably 50-90 ° C. for 3-7 minutes, more preferably 65-75 ° C. for 3-7 minutes, reduction gold plating, preferably 55-65 ° C. for 7-15 minutes. The gold plating film layer can be formed by preferably carrying out at 58 to 62 ° C. for 7 to 15 minutes.

[Fluorine passivation film]
By fluorinating the surface of the gold plating film layer in the step (C), the pinholes of the gold plating film layer are sealed by the fluorinated passivation film.

The fluorinated passivation film is formed only on the exposed surface of the nickel-phosphorus alloy plating layer (2b) in FIG. 1 (b). That is, it is formed while growing only in the vertical direction of the fluorinated passivation film 5, and is not formed on the inner side surface of the pinhole of the gold plating film layer 3 or on the outermost surface of the gold plating film layer 3, and is also gold. It does not exceed the upper end of the plating film layer 3.

The thickness of the fluorinated passivation film is usually 8 nm or more, preferably 10 to 20 nm, and more preferably 12 to 18 nm. When the thickness of the fluorinated passivation film is within the above range, the durability of the fluorinated passivation film and the like are practically suitable. The thickness of the fluorinated passivation film here is the length of the obtained laminate in the stacking direction, and is, for example, the length of the fluorinated passivation film 5 in the vertical direction in FIG. 1 (b). ..

<Process (C)>
In the step (C), the surface of the nickel-containing plating film layer exposed from the pinholes of the gold plating film layer that has undergone the steps (A) and (B) is fluorinated by forcibly fluorinated using a fluorinated gas. A passivation film is formed and the pinholes are sealed.

The step (C) is carried out in an atmosphere where the fluorine gas concentration is preferably 8% by volume or more, more preferably 10 to 25% by volume, and the fluorine temperature is preferably 100 to 150 ° C., more preferably 105. It is 145 ° C, more preferably 110 to 140 ° C.

The fluorogas is at least one gas selected from the group consisting of _{fluorine (F 2} ), chlorine trifluoride (ClF ₃ ) and nitrogen trifluoride (NF ₃ ) as the gas used for the fluoride treatment. Alternatively, it is a general term for gases obtained by diluting this gas with an inert gas.

For example, when chlorine trifluoride is used, it can be thermally decomposed at 60 to 100 ° C. to generate fluorine radicals, and these radicals can be used for the fluorine reaction. When nitrogen trifluoride is used, it is decomposed by plasma energy to generate fluorine radicals, and these radicals can be used for the fluorination reaction.

Examples of the diluting gas accompanying the fluoride gas include an inert gas such as nitrogen gas and argon gas, and nitrogen gas is preferable.
When the fluorine gas is diluted and used, its concentration can be appropriately set depending on the reaction conditions. For example, in the case of fluorine, it is preferable to use it at a concentration of about 10% in consideration of cost and the like.

When the metal base material is stainless steel, it is preferably fluorinated at 150 to 190 ° C., more preferably 155 to 175 ° C., and when it is an aluminum alloy, it is fluorinated at preferably 140 to 160 ° C., more preferably 145 to 155 ° C. When the film formation temperature is within the above range, the heat diffusion between electroless nickel-alloy plating and gold plating is well balanced.

The fluorination treatment time varies depending on the thickness of the fluorinated passivation film to be formed, but is preferably 20 to 100 hours, more preferably 30 to 80 hours in order to exhibit excellent corrosion resistance.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

[Example 1]
<Process (A)>
The surface of stainless steel (SUS316L) processed into a test piece size of 15 mm in length × 15 mm in width × 1 mm in thickness was subjected to degreasing, acid cleaning and nickel strike treatment as pretreatment. The acid cleaning was carried out at room temperature for 25 seconds using hydrochloric acid as a cleaning agent. An electroless nickel-phosphorus plating agent "Nimden (trademark) NSX" (manufactured by Uemura Kogyo Co., Ltd.) was used on the surface of the nickel strike-treated stainless steel, and the plating temperature was 90 ° C., pH 4.5-4. Under the conditions of 0.8, an electroless nickel-phosphorus alloy plating film layer (1) having a phosphorus content of 8% by mass or more and less than 10% by mass at the time of film formation was formed at a film formation rate of 10 μm / 25 minutes. Next, using an electroless nickel-phosphorus plating agent "Nimden (trademark) HDX" (manufactured by Uemura Kogyo Co., Ltd.), the phosphorus content at the time of film formation was 10% by mass or more at a film formation rate of 10 μm / 50 minutes. An electroless nickel-phosphorus alloy plating film layer (2) of 12% by mass or less was formed. As a result, a nickel-containing plating film layer having a total thickness of 20 μm was formed on the nickel strike-treated stainless steel.

<Process (B)>
Two types of electroless gold plating solutions "Flash Gold NC (replacement type)" and "Self Gold OTK-IT (reduction type)" (both manufactured by Okuno Pharmaceutical Co., Ltd.) are used in this order. The nickel-containing plating film layer formed in A) was treated in this order at a replacement plating temperature of 70 ° C. for 5 minutes and a reduction plating temperature of 60 ° C. for 10 minutes, respectively, to achieve a total thickness of 0.6 μm thick gold plating film. A layer was formed.

<Process (C)>
The stainless steel having the nickel-containing plating film layer and the gold plating film layer formed in the steps (A) and (B) was mounted inside the normal pressure gas phase flow reactor, and the temperature inside the furnace was raised to 115 ° C. .. Then, the atmosphere was replaced with nitrogen gas, and then 10% by volume fluorine gas diluted with nitrogen gas was introduced to replace the nitrogen gas in the reaction furnace with 10% by volume fluorine gas. After complete replacement, the state was maintained for 36 hours, and the exposed portion of the electroless nickel-phosphorus coating underneath due to the pinholes generated during gold plating was forcibly fluorinated to form a fluorinated passivation coating. .. When the obtained passivation film was analyzed by W-SEM "JSM-IT200" (manufactured by JEOL Ltd.), it was confirmed that the film thickness of the passivation film was 10 nm. The film thickness of the fluorinated passivation film here is the length of the obtained laminate in the stacking direction, and is, for example, the length of the fluorinated passivation film 5 in the vertical direction in FIG. 1 (b). is there.

[Example 2]
In the step (C) of Example 1, the fluorinated inert film was formed in the same manner as in Example 1 except that the forced fluorination time using 10% by volume fluorinated gas diluted with nitrogen gas was changed to 72 hours. It was formed. When the film thickness of the obtained fluorinated passivation film was determined in the same manner as in Example 1, it was confirmed that the film thickness was 13 nm.

[Example 3]
In Example 1, an aluminum alloy (A5052) was used instead of stainless steel (SUS316L), and after performing degreasing, activation treatment, acid cleaning and zinc substitution treatment as pretreatment, the same method as in Example 1 was performed. Steps (A) and (B) were carried out.

The activation treatment was carried out at room temperature for 30 seconds using a mixed acid of acidic ammonium fluoride and nitric acid as a treatment agent. The acid cleaning was carried out at room temperature for 25 seconds using nitric acid as a cleaning agent. The zinc substitution treatment was carried out at room temperature for 25 seconds using a zincate bath as a treatment agent. The acid cleaning and the zinc replacement treatment were performed twice under the above conditions.

In step (C), a fluorinated passivation film was formed on the gold-plated film in the same manner as in Example 2 except that the forced fluorine temperature was set to 105 ° C. When the film thickness of the obtained fluorinated passivation film was determined in the same manner as in Example 1, it was confirmed that the film thickness was 10 nm.

[Comparative Example 1]
Only the step (A) of Example 1 was carried out to form a total nickel-containing plating film layer of 20 μm on the surface of the stainless steel.

[Comparative Example 2]
After performing the steps (A) and (B) of Example 1, the stainless steel having the nickel-containing plating film layer and the gold plating film layer was exposed to the atmosphere to form a natural oxide film. When the film thickness of the obtained natural oxide film was determined in the same manner as in Example 1, it was confirmed that the film thickness was 7 nm.

[Comparative Example 3]
After carrying out the step (A) of Example 1, the following treatment was carried out. Stainless steel having a nickel-containing plating film layer was mounted inside a normal-pressure gas-phase flow reactor, and the temperature inside the furnace was raised to 300 ° C. Then, the atmosphere was replaced with nitrogen gas, and then 100% by volume oxygen gas was introduced to replace the nitrogen gas with oxygen gas. After complete replacement, the state was maintained for 12 hours. Next, 10% by volume fluorine gas diluted with nitrogen gas was introduced, and the state was maintained for 12 hours to form a _{nickel fluoride (NiF 2) film on the nickel-containing plating film layer.} Then, nitrogen gas was injected for 12 hours to stabilize the film formation.

[Evaluation]
The coating films on the surface of the metal substrate obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were evaluated by the following methods. The evaluation results are shown in Table 1.

<Hydrochloric acid corrosion resistance test>
A test piece having a length of 15 mm, a width of 15 mm, and a thickness of 1 mm was immersed in a 35 mass% hydrochloric acid solution at 25 ° C. for 5 hours. Hydrochloric acid corrosion resistance was evaluated according to the following criteria based on the amount of mass loss [mg / dm ^{2] before and after immersion.}
(Evaluation criteria)
A: Less than 0.1 mg / dm ² B: 0.1 mg / dm ² or more and less than 3 mg / dm ² C: 3 mg / dm ² or more

In the table, SUS indicates stainless steel (SUS316L) and Al indicates an aluminum alloy (A5052).

1 ... Metal substrate 2 ... Nickel-containing plating film layer 2a ... Nickel-phosphorus alloy plating layer (1)
2b ... Nickel-phosphorus alloy plating layer (2)
3 ... Gold plating film layer 4 ... Pinhole 5 ... Fluorine passivation film

Claims

It has a metal base material, a nickel-containing plating film layer formed on the metal base material, and a gold plating film layer formed on the nickel-containing plating film layer.
A laminate in which the pinholes of the gold-plated coating layer are sealed by a fluorinated passivation coating having a thickness of 8 nm or more.
The laminate according to claim 1, wherein the metal base material contains at least one metal selected from the group consisting of stainless steel, iron, aluminum, aluminum alloys, copper and copper alloys.
The laminate according to claim 1 or 2, which has a nickel strike layer between the metal base material and the nickel-containing plating film layer.
The nickel-containing plating film layer includes a nickel-phosphorus alloy plating layer (1) having a phosphorus concentration of 8% by mass or more and less than 10% by mass, and a nickel-phosphorus alloy plating layer (1) having a phosphorus concentration of 10% by mass or more and 12% by mass or less. The laminate according to any one of claims 1 to 3, wherein 2) is contained in this order from the metal base material side.
The laminate according to any one of claims 1 to 4, wherein the gold plating film layer contains a replacement type gold plating film layer and a reduction type gold plating film layer in this order from the nickel-containing plating film layer side. ..
A component of a semiconductor manufacturing apparatus, which comprises the laminate according to any one of claims 1 to 5.
Step (A) of forming a nickel-containing plating film layer on a metal substrate,
A step (B) of forming a gold plating film layer on the nickel-containing plating film layer, and a sealing treatment step (C) of forming a fluorinated passivation film having a thickness of 8 nm or more in the pinholes of the gold plating film layer. ), A method for producing a laminate.
The method for producing a laminate according to claim 7, wherein the sealing treatment step (C) is performed in an atmosphere having a fluoride gas concentration of 8% by volume or more and a temperature of 100 to 150 ° C.
The method for producing a laminate according to claim 7 or 8, wherein the metal base material contains at least one metal selected from the group consisting of stainless steel, iron, aluminum, aluminum alloys, copper and copper alloys.
The laminate according to any one of claims 7 to 9, further comprising a step of subjecting the metal substrate to a nickel strike treatment under the condition of a current density of 5 to 20 A / dm 2 before the step (A). Production method.
The step (A) is a step (a1) of forming a nickel-phosphorus alloy plating layer (1) having a phosphorus concentration of 8% by mass or more and less than 10% by mass, and after the step (a1), the phosphorus concentration is 10% by mass. The method for producing a laminate according to any one of claims 7 to 10, further comprising a step (a2) of forming a nickel-phosphorus alloy plating layer (2) of% or more and 12% by mass or less.
7. The step (B) includes a step (b1) of forming a replacement mold plating film layer and a step (b2) of forming a reduction die plating film layer after the step (b1). The method for producing a laminate according to any one of 11 to 11.